Piano hammer felt press



Sept. 24, 1957 c. w. TUCKER ETAL PIANO HAMMER FELT PRESS 3 Sheets-Sheet 1 Filed Aug. 10. 1955 IN VEN TORS (A fiAE/Vff W. 70mm.

Sept. 24, 1957 Filed Aug. 10, 1955 C- W. TUCKER ETAL PIANO HAMMER FELT PRESS 3 Sheets-Sheet 2 IN V EN TORS P 1957 c. w. TUCKER ETAL 2,807,295

PIANO HAMMER FELT PRESS Filed Aug. 10, 1955 3 Sheets-Sheet 3 BYCZ/FFJRP m/Momxm flrromvas,

United States Patent Qfiice Patented Sept. 24, 1957 PIANO HAMMER FELT PRESS Clarence W. Tucker, Sycamore, and Clifford W. Andersen, De Kalb, Ill., assignors to The Rudolph Wurlitzer Company, Chicago, 111. a corporation This invention relates to a press forgluing felt on piano hammers, either as an under felt or an outer felt.

In the production of piano hammers, the individual hammers are sliced to the proper width from an elongated molding of sufiicientlength to accommodate one entire set of hammers. The hammer tnoldingis formed of wood shaped to provide in cross section the hammer body and shank to which the usual felt' cushions are applied. The felt is similarly formed in elongated'strips tapering in width and thickness from one end to the other with both sides suitably heveled'to a feathered edge, as more particularly shown and described in our copending application for Letters Patent filed July 29, 1955, Serial No. 525,299, entitled Apparatus for Cutting Felt.

This invention contemplates a suitable press or jig in which a wooden hammer molding may be removably secured with its shank portion extending downwardly toward a strip of felt positioned in the press. Glue is applied in any suitable manner, as by brushing over the exposed shank portion of the molding, whereupon the molding is forced downwardly and centrally of the felt strip to depress it and cause the side edges to flare upwardly about opposite sides of the shank portion. Thereupon, opposed electrically heated side clamps or cauls are forced laterally and inwardly against the flared edges of the felt to pinchit upwardly and against the exposed side portions of the molding. Said heated cauls are held in their clamping or pinching position for a predetermined period of time to cause the glue to be set and cured. Following such setting and curing of the glue, and with the felt strip thus permanently secured in embracing relation with the shank portion of the molding, the side cauls are released and withdrawn and the molding raised to a position for removalfrom the press with the felt strip carried thereby. If the applied felt is the under felt of the hammers, the same operation is proceeded with on another press to similarly apply the outer felt thereabout. After the outer felt is thus applied, the felted molding is ready for slicing into a set of piano hammers.

The full nature of the invention will be understood from the accompanying drawings and the following de} scription and claims: p i

Fig. 1 is a perspective View with a portion broken away, showing the hammer molding secured in its carrying frame before applying the felt.

Fig. 2 is a similar view showing the felt'strip' to be applied to the hammer molding. v I

Fig. 3 is the same view showing the hammer molding with the felt applied thereto and indicating by dotted lines the slicing thereof into individual hammers.

Fig. 4 is illustrative of the step by step gluing operation.

Fig. 5 is a side elevation of the press; in its released position. i

Fig. 6 is a view taken onthe line 6-6 of Fig. 5.

Fig. 7 is an end elevation viewed from the right-hand end of Fig. 5.

Fig. 8 is a wiring diagram of the electric control.

, In the drawings for illustrating the purpose and functioning of the press, there is shown in Fig. 1 a portion of .a wooden piano hammer molding 10 having a body portion 11 and a reduced shank portion 12. Said moldings are individually mounted in a carrying frame comprising a pair of opposed clamping plates 13 adapted to embrace and clamp the body it) of the'molding through the medium of a series of bolts 14 and an intermediate spacer 'bar 15, there being provided a friction strip, such as felt, indicated at 16, between one side of the body 11 and a plate 13, as illustrated in Fig. 6.

The felt strip 17 is shown in Fig. 2, having beveled side walls 18 tapering to feathered edges 19 and adapted to be wrapped around the shank portion 12 and glued thereto as shown in Fig. 3. The press for effecting the wrap around of the felt and clamping it about the shank'portion of the hammer molding until set and cured, is shown in Figs. 5, 6, and 7. g

The press comprises a frame structure, including upright supports 20, extending the length of the hammer molding and set'of piano hammers to be sliced therefrom. Supported by the cross struts 22 there is a frame 23 mounting an elongated wooden die block 24 formed with a longitudinally extending and centrally disposed V-shaped groove 25. The die block is of a dimension to receive and support the felt strip 17, which spans the groove 25.

Immediately above the die block 24 and centrally aligned with the groove 25 there is provided a ram assembly 26 movably mounted on the frame structure and having a series of notches 27 provided in the lower edge thereof. At each end of the ram assembly there are elongated clamping springs 28 bolted thereto at 29 with their ends bearing against locking balls 30, as shown in Fig. 5. The lower portion of the ram assembly is bifurcated to slidably receive the carrying frame 13 of the molding 11 with its clampingbolts 14 being accommodated in the notches 27. Upon the molding and its carrying frame being slipped into position within the ram assembly it will be gripped and held therein under pressure of thelocking balls 30. This arrangement permits the-carrying frame and its moldingto be readily slipped from the ram assembly following completion of the gluing operation. a

Hinged to opposite sides of the ram assembly there is a pair of guard plates 31 adapted to be swung upwardly out of the way when inserting or removing the molding; When swungdownwardly their lower edges are adapted to engage with the positioned molding immediately above the shank portion 12 to protect the upper body portion 11 from the application of glue. With the guard plates in their lower position, the exposed portion of the molding may be brushed on both sides of its shank portion with a coating of suitable adhesive.

The ram assembly is mounted at opposite ends of the piston rods 32 extending downwardly between the uprights 20, each terminating with a piston operating in a pneumatic cylinder 33. The upper ends of said cylinders are connected by the lines 34 'with' a control, valve mounted within a valve housing 35 carried by a p lat= form on a cross frame member 36. The lower ends of said cylinders are connected by the lines 37 to saidvalve. Said valve in turn is connected with a suitable source of air pressure, not shown, so that when the valve is moved in one direction air under pressure is admitted to the tops of the cylinders for forcing the ram assembly down: wardly to effect a gluingoperation, as hereinafter de-,' scribed. 'When the valve is moved to the opposite position air is admitted to the bottom of the cylinders 33 for raising the ram assembly following the completion of the gluing operation. 1

The said air valve in housing 35 is controlled 'bya plunger 38 which in turn is actuated by a lever39 pivoted at one end to the valve housing 35 at 40. The

3 opposite end of the lever is connected by a link 41 to a core 42 of the ram operating solenoid 43. As hereinafter described, when solenoid 43 is energized it pulls the lever, 39 downwardly against the tension of the compression spring 44, moving the air valve, through the plunger 38, to open the source of air pressure ,through lines 34 to cylinders 33. The ram assembly is then forced downwardly for the gluing operation. Upon the solenoid 43 being deenergized, the spring 44 raises the lever, for positioning the valve to close off line 34 and open line 37, returning the ram assembly to its initial inoperative position.

Slidable in the ways 21 at each end of the frame structure there is a pair of opposed clamping plates or side cauls 45. Each plate has secured thereto along its inner edge a heating element 46 known by the trade name Nilvar through which a heavy electric circuit is passed from a transformer. The clamping plates are so arranged that when in their normal inoperative position they are spaced apart to receive between them the felt strip 17 supported along the die block 24. 'When said plates are forced toward each other, they engage the upwardly bowed side portions of the dished felt for bending it about, and clamping it securely against, the sides of the molding shank, as hereinafter described.

Opposite ends of the clamping plates are pivotally connected through the pins .47 to the adjustable links 48, each carrying at its opposite end a pin 49. Said pins are respectively engaged by the upper ends of a pair of levers 50, each being fulcrumed at 51 to a cross bar 52. The lower ends of said levers are pivotally connected at 53 to the links 54 which in turn are pivoted at 55 to an adjustable yoke 56 carried by a piston rod 57 operative by a piston in an air cylinder 58, there being two air cylinders and lever assemblies, as shown in Fig. 5.

The upper ends of said cylinders are connected through lines 59 with an air valve housing 35, the lower end of said cylinders being connected therewith through the air lines 60. The air valve controlling the lines 59, 60 is operated through a plunger 61 by the lever 62, which lever is connected by a link 63 to the core 64 of a clamping plate solenoid 65. The forward end of the lever 62 is pivoted at 40 on the housing 35. When the solenoid 65 is energized, said lever actuates the plunger 61 to open the air valve from a source of air pressure through the line 59 to force the clamping plates toward each other in, their clamping direction. When said solenoid is deenergized a compression spring 66 returns the lever, whereupon the valve will be positioned to admit air through the line 60 which will cause the air cylinders to retract the clamping plates.

As illustrated in Fig. 4, the felt is laid upon the die block 24,3spanning the recess 25, with the shank 12 of the molding positioned to be moved downwardly into engagement therewith centrally of and in alignment with i said recess, as illustrated in the first position of Fig. 4. As shown in the second position of Fig. 4, the shank 12 has forced the felt downwardly into the recess 25 under the pressure exerted by the ram assembly through the medium of the air cylinders 33 actuated by energizing the solenoid 43. With the felt thus depressed, the sides thereof will bow upwardly, whereupon the clamping plates will be forced inwardly thereagainst under pressure of the cylinders 58 upon solenoid 65 being energized. Through the side pressure exerted by said clamping plates, the felt will be folded about the shank 12, in contact with the applied glue or other suitable adhesive as shown in the third position of. Fig. 4. In this position current is introduced through the heating elements 46 over 'a predetermined period of time to effect the final setting and curing of the glue for retention of the felt.

In the control box 67 (Fig. 5) there is provided a series of switch buttons A, B, C, D and E. Referring to Fig. 8, buttons A and E are operated to close and open the switch 68 for making and breaking a circuit through solenoid 43, respectively. The switch buttons B and D are operated to close and open the circuit through the solenoid 65, respectively. The push button C is operated to close a circuit through the timer 70 which energizes the heating elements 46, during which a signal lamp 71 is ener gized. The circuit through the heating elements 46 remains closed by the timer switch for a predetermined period of time, approximately twelve minutes, to complete the setting of the adhesive, whereupon the circuit is automatically broken through the heating elements and the signal lamp. Upon blanking out of the signal lamp, the operator then operates switch button D to deenergize solenoid 65 for retracting the clamping plates. The push button E is then operated to deenergize solenoid 43, whereupon the ram assembly is elevated. The felted hammer molding isthen removed from the ram assembly and replaced by a new molding ready for the next felting operation.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being had to the appended claims.

The invention claimed is:

1. A press for felting piano hammers comprising a frame structure mounting an elongated die block having a centrally disposed groove extending longitudinally thereof for receiving a strip of felt, a ram assembly movably mounted on said structure adapted to receive and support an elongated hammer molding having a shank portion, a pair of guard plates each hingedly mounted on opposite sides of said assembly movable into position for embracing a portion of said molding with said shank portion exposed for receiving and limiting the application of an adhesive coating thereover, means for moving said assembly and molding to and from said block and felt with the said shank portion in alignment with said groove for depressingthe central portion of said felt therein under pressure and how its side portions outwardly therefrom, a pair of opposed clamping plates movable on said structure into and out of position to engage and clamp the bowed side portions of said felt about the adhesive coated shank portion of said molding, heating elements on the felt engagingedges of said plates, and means operable to hold said plates in felt clamping position and energize saidelements over a predetermined period of time to effect the adhesion of said felt to the exposed shank portion of said molding.

2. A press for felting piano hammers comprising a frame structure mounting an elongated die block having a centrally disposed groove extending longitudinally thereof for receiving a strip of felt, a ram assembly movably mounted on said structure adapted to receive and support an elongated hammer molding having a shank portion, a pair of guard plates each hingedly mounted on opposite sides of said assembly movable into position for embracing a portion of said molding with said shank portion exposed for receiving and limiting the application of an adhesive coating thereover, means for moving said assembly and molding to and from said block and felt with the said shank portion in alignment with said groove for depressing the central portion of said felt therein under pressure and how its side portions outwardly therefrom, and a pair of opposed clamping plates movable on said structure into and out of position to engage and clamp the bowed side portions of said felt about the adhesive coated shank portion of said molding.

3. A press for felting piano hammers comprising a frame structure mounting an elongated die block having a centrally disposed groove extending longitudinally thereof for receiving a strip of felt, a ram assembly movably mounted on said structure adapted to receive and support an elongated hammer molding having a shank portion, means for embracing a portion of said tions of said felt about the adhesive coated shank poimolding with said shank portion exposed for receiving tion of said molding.

and limiting the application of an adhesive coating there- References Cited in the file of this Patent over, means for moving said assembly and molding to and from said block and felt With the said shank por- 5 UNITED STATES PATENTS tion in alignment with said groove for depressing the 361,144 Dolge Apr. 12, 1887 central portion of said felt therein under pressure and bow 661,398 Eaton Nov. 6, 1900 its side portions outwardly therefrom, and a pair of op- 1,879,464 Pfriemer Sept. 27, 1932 posed clamping plates movable on said structure into and 2,171,977 FTiZ P 5, 1939 out of position to engage and clamp the bowed side por- 10 2,322,952 Dickson June 29, 1943 

